Re: How to do numerical computations?

*To*: mathgroup at smc.vnet.net*Subject*: [mg108813] Re: How to do numerical computations?*From*: dr DanW <dmaxwarren at gmail.com>*Date*: Thu, 1 Apr 2010 06:01:58 -0500 (EST)*References*: <hov834$94q$1@smc.vnet.net>

I'm taking a guess that you have a fairly complicated Block[] or Module[] with an integration that involves some parameters. Mathematica is hitting that integration and trying to evaluate it symbolically, which can be time consuming. I think what you want to do is prevent that integration from evaluating until it gets numerical values for the parameters. One way to do this is to create a function out of the integration that requires numerical input. A trivial example is int[a_?NumericQ] := NIntegrate[ Sin[x] , {x, 0, a} ] This way, when you say b = int[c] where c has no value, Mathematica will hold it as int[c] and not attempt a symbolic evaluation. Later, you can say c = 3., and the numerical integration can be evaluated quite quickly. Daniel